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Abstract: Abstract Digital twins use actual sensor data to replicate the current state of a plant in a virtual model. They can be used to evaluate the current state, predict future behavior, and thus allow to refine control or optimize operation, enable predictive maintenance as well as detection of anomalies and failures. The model of a digital twin includes models of the components, behaviors and dynamics of a system. With the ability to simulate real scenarios, such models can therefore also be used before a plant is actually implemented, e.g., to predict the actual performance, identify potential issues for the implementation and to develop optimal operation strategy and algorithms. Furthermore, interfaces may be defined, implemented, and tested with such models allowing fast and easy commissioning of the physical implementation. Accurate digital twins therefore also need to include realistic sensor models, considering adverse effects that impact their output signals. The proposed work presents approaches for accurate sensor simulations allowing researchers and industries to assess sensor performance, optimize algorithms, and evaluate system-level integration. We address Frequency Modulated Continuous Wave (FMCW) radar sensors and time-of-flight cameras as examples for far-field sensors and capacitive sensors as an example for near-field sensors. The approaches can be transferred to other sensors, e.g., ultrasound sensors, LiDAR sensors and inductive or magnetic sensors so that a wide range of industrial sensors can be covered. The proposed simulations are benchmarked with different tests, including real-world experiments and compared with the corresponding real sensors. PubDate: 2023-09-25
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Abstract: Abstract This paper presents a method for planning time-optimal trajectories for a formation of multiple nonholonomic (heavy duty) platforms (HDPs) to cooperatively transport an object to a specified pose. The first part addresses the mobile platforms themselves while the second part provides a trajectory planning approach derived from the well-known virtual leader approach. In order to ensure proper transport of the shared payload, the vehicles are modeled individually, resulting in a formation control problem. The goal of the optimization process is to minimize a cost function that balances time optimality, smooth control signals, and formation rigidity. The optimal control problem (OCP) takes into account the kinematics of the vehicles as well as their physical limitations. It is solved by using a multiple shooting method, which yields the desired trajectories for all vehicles while ensuring smooth control signals. The paper includes optimization results for several scenarios involving two and three HDPs together with various target poses, demonstrating the effectiveness of the proposed method. PubDate: 2023-09-25
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Abstract: Zusammenfassung Während matte Objekte visuell gut erkannt und mit Robotern gegriffen werden können, stellen transparente Objekte neue Herausforderungen dar. So liefern moderne Farb- und Tiefenbildkameras (RGB-D) keine korrekten Tiefendaten, sondern verzerrte Abbildungen des Hintergrunds. Wir zeigen in diesem Beitrag, welche Methoden geeignet sind, um nur in Farbbildern transparente Objekte zu erkennen und deren Pose zu bestimmen. Mittels eines Robotersystems werden Ansichten des Zielobjekts generiert und annotiert, um Methoden anzulernen und um Daten für die Evaluierung zu erhalten. Wir zeigen auch, dass mittels einer verbesserten Methode zum Einpassen der 3D-Pose eine deutliche Verbesserung der Genauigkeit der Lageschätzung erreicht wird. Dadurch können falsche Erkennungen aussortiert werden und für richtige Erkennungen wird die Genauigkeit der Poseschätzung verbessert. Somit gelingt es, mit einem Roboter transparente Objekte zu greifen. PubDate: 2023-09-12
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Abstract: Zusammenfassung Sicherheit, also Personen- sowie Informationssicherheit, ist eine der wichtigsten Anforderungen an jede Maschine und Anlage. Die Maschinenrichtlinie 2006/42/EG regelt das Inverkehrbringen von sicheren vollständigen und unvollständigen Maschinen. Ende Juni 2023 wurde die EU-weite Maschinenverordnung veröffentlicht, die die Maschinenrichtlinie in Zukunft ersetzen wird. Diese Neuerung ist für alle Maschinenbereiche von Relevanz. Speziell für die Robotik herrscht aktuell außerdem eine starke Revision im Bereich der Normierung. Zum einen wurde die ISO 13849, die meist verbreitete ISO-Norm für funktionale Sicherheit, erneuert. Zum anderen wird die ISO 10218, jene Norm, die die Anforderungen für den Entwurf von Industrierobotern und die Integration von deren Applikationen regelt, überarbeitet. Dieser Beitrag gibt einen Einblick in die aktuellen Trends und Revisionen der europäischen Normen und Richtlinien, die für stationäre Industrieroboter und deren Applikationen relevant sind. PubDate: 2023-09-07
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Abstract: Abstract In this paper we describe the concept and ongoing work of the research project MOBILIZE, which addresses the operational safety and security of large railway systems to prevent sabotage and vandalism. Examples of such acts are manipulation of system components, intentional placement of objects on the tracks, theft of copper cables or damage to property such as graffiti on parked trains. The prevention of personal injuries resulting from crossing tracks or climbing on parked wagons and thereby getting too close to or even touching the overhead lines is also an important aspect. A permanent installation of video surveillance systems for the entire railway infrastructure is not feasible and, what is more, state-of-the-art video surveillance alone is currently not up to the challenges of monitoring very large areas completely. Therefore, MOBILIZE focuses on the development of a reliable portable system with multi-sensor modalities. In case of increased incidents in a specific region, the system can be deployed quickly and easily. The development of such a system raises questions that represent the main scientific challenges to be explored within MOBILIZE: which combination of sensor technologies is the most suitable to reduce false alarm rates to a minimum in practical operation, legal issues such as the changing regulations regarding the usage of drones, usability for the operator, integration into the operational procedures of the railway operators as well as future economic exploitation of the MOBILIZE project. The current paper focuses on the work done on ground-based visual sensors as well as their fusion with other sensors employed within MOBILIZE, and an assessment of their social impact. PubDate: 2023-09-01
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Abstract: Abstract This is the first of a series of papers on novel methods for the calculation of eddy current losses in permanent magnets (PMs) and the shortcomings of previously conducted analyses. Eddy current losses in PMs and their mitigation are significant factors when designing inverter-fed electric drives. Especially with the need for drives with high power density, a trend toward increased rotational speeds and, therefore, higher fundamental frequencies and inverter switching frequencies are observable. Higher harmonic frequency components of concentrated windings and fractional slot windings are widely taken into account when designing rare sintered earth magnets for permanent magnet synchronous machines (PMSMs). However, inverter-related losses are rarely simulated in Finite Element Method (FEM) co-simulations and can contribute as a major factor to the power losses in PMSMs. In the worst case, this neglection can lead to the thermal demagnetization of the permanent magnets. Segmentation provides an effective measure to limit eddy current losses. However, not every kind of segmentation proves effective in a drive application. Depending on the frequency behavior of the magnetic flux in a permanent magnet, segmentation can increase eddy current losses within the magnet compared to a non-segmented magnet. This behavior is due to the reaction to the flux caused by the eddy currents within the magnet. The reaction of the eddy currents is often neglected [1, 2], and, in other cases, the vicinity of ferromagnetic material is neglected in analytical calculations [3] but proves crucial for the exact calculation of higher frequency losses [4, 5]. In this paper, an analytical solution to calculate harmonic eddy current losses in permanent magnets, including the reaction flux with homogeneous excitation, is given. PubDate: 2023-08-08
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Abstract: Recent advancements in energy systems, such as the emergence of prosumers and sector coupling approaches, introduce additional flexibilities over multiple energy sectors, such as heating, electricity, and mobility. Due to the complexity of such distributed systems, the optimization of energy allocation is a non-trivial task, especially considering constraints and limitations introduced by distributed devices or sub-systems. Additionally, the variety of devices forces approaches to be highly situational and not universally applicable. In this paper, a two-level optimization scheme is proposed, which aims at reducing the optimization complexity of sector-coupled systems. The multi-vector optimization embedded in the two-level optimization scheme is formulated as a mixed-integer linear problem, optimizing the energy flow between domains, which are modeled as an abstraction of a sector. Distributed devices are modeled as components that represent an abstraction of devices connected to an energy domain. The optimization process is evaluated based on the data from a residential complex in Ghent, Belgium. It shows that the approach is capable of minimizing costs, \(\text{CO}_{2}\) emissions, and dependency on external resources. PubDate: 2023-08-04
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Abstract: Abstract This is the second of a series of papers on new methods for the calculation of eddy current losses in permanent magnets (PMs) and the shortcomings of previous analyses. Our first paper extended Ruoho’s work on harmonic field distributions to the reaction field of eddy currents within permanent magnets. The approach was based on the methods of the harmonic complex AC calculation. In this paper, the models presented in our previous paper are further extended to allow a harmonic calculation of eddy current losses in permanent magnets for homogeneous fields, including the effects of eddy current losses in an adjacent ferromagnetic material, leakage flux factors, and non-constant inductance. PubDate: 2023-08-04
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Abstract: Abstract To ensure continued reliable operation of the energy grid in the face of a rising number of local energy communities (LECs), they need to be integrated in a way that ensures that they do not negatively impact but rather support the overall system, e.g., by providing flexibility. Project ECOSINT aims at intelligent, digital integration of LECs to achieve this goal. Along with several other tasks, this includes the development of a suitable software architecture, which is currently in progress and has yielded a conceptual model as a first result. Among the numerous requirements regarding LECs and their software architecture which have been collected in the initial phase of the project, interoperability has been identified as a crucial factor for success. This is addressed by incorporating AIT’s virtual lab (VLab) framework, which is presented and demonstrated using the example of an electric vehicle (EV) charging scenario as part of the ECOSINT solution. PubDate: 2023-08-04
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Abstract: Abstract Due to the new digital control structures of cyber-physical energy systems (CPES), where the control interventions no longer take place physically on site but are triggered, released, executed and acknowledged remotely by automated control systems, there is not only the risk of incorrect actions by plants or operators, but also of possible attacks or misuses. In this contribution, we propose an integrated security-by-design approach (on a conceptual level) for testing the interoperability of various heterogeneous systems (e.g., TSO-DSO communications) by combining multiple, but yet separated, state-of-the-art approaches. With the objective of eliminating or minimizing the impact of cyber incidents, best practices from various sectors have been adapted and integrated with well-established methods and standards from the energy sector, such as the IEC 62559‑2 use case template. PubDate: 2023-07-28
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Abstract: Abstract The need for a more sustainable energy system is leading to more electric energy generation being connected to low voltage (LV) distribution grids. At the same time, due to accelerated growth in electric mobility and heat pumps, more and more energy consumed by end customers is supplied via LV distribution grids. These developments cause distribution networks to become less predictable and make them subject to much higher changes in supply and demand. Therefore, additional flexibility will be needed to keep such systems operating with high quality of service. The required flexibility could be provided by distributed generators as well as flexible loads. This leads to the question of how these flexibilities can be activated by distribution system operators when needed. A digital interface between distribution system operator and device operator could be implemented to communicate flexibility requirements. In this work, three possible deployment scenarios for such a digital interface are presented. A market review of available standards and commonly implemented communication protocols was conducted to identify potential candidates for the standardization of such an interface. PubDate: 2023-07-28
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Abstract: Abstract The novel Energy Community (EC) concept introduces communal incentives for citizens to monitor and control energy usage. This circumstance brings up the need for digitalized solutions that support EC members in optimizing their energy usage. While research and industry already came up with concepts to tackle this problem, interoperability aspects of Information and Communication Technology (ICT) infrastructures are rarely investigated. As a result, the diverse protocol landscape of energy-related devices slows down technological penetration and consequently hinders the modernization of ECs. For this reason, the following paper proposes an architecture design that addresses interoperability problems in ECs by bundling communication issues into services that utilize the Web of Things (WoT) standard. Furthermore, the architecture design is demonstrated in a testbed environment where a WoT-compatible Electric Vehicle (EV) charging station and a legacy inverter are integrated. PubDate: 2023-07-14
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Abstract: Abstract This paper discusses the development and use of a cyber range scenario for teaching cyber security in the energy sector, specifically in the smart grid. The scenario focuses on testing the DLMS standard for electricity metering using virtual smart meters and concentrators. The aim is to demonstrate the security issues of these devices, how they can be compromised, and to prevent the theft of sensitive personal data or, in extreme cases, even disconnection of the customer’s electricity. The paper describes the use of this scenario in a teaching context and highlights its importance in raising awareness of cyber security in the energy sector. PubDate: 2023-07-14
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract This paper deals with the determination of electromagnetic forces in permanent magnet synchronous machines (PMSMs) and their influence on the noise, vibration, and harshness (NVH) behavior of a drive system. Electromagnetic forces, i.e., forces in the stator teeth and the rotor, can be determined by evaluating the air gap flux density. The air gap flux density is obtained through a time-dependent FE simulation and can be presented as a 2D matrix over time and space. The time and spatial harmonics of this matrix are calculated with the complex 2D FFT. The results are illustrated as clear bubble plots, which make it easy to determine critical harmonics. Moreover, the identified problematic harmonics are plotted either over the complete torque speed map or over the currents id and iq. The latter representation can be used to determine NVH-optimized id∕iq combinations that deviate from the usual MTPA (maximum torque per ampere) current combinations. PubDate: 2023-05-09 DOI: 10.1007/s00502-023-01138-0
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